/**
 * Created with IntelliJ IDEA.
 * Description:最长公共子串
 * User: wangxin
 * Date: 2025-01-20
 * Time: 21:08
 */
public class Teat {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * longest common substring
     * @param str1 string字符串 the string
     * @param str2 string字符串 the string
     * @return string字符串
     */
    public String LCS (String str1, String str2) {
        // write code here
        int n = str1.length();
        int m = str2.length();
        int maxLength = 0;
        int maxLastIndex = 0;
        int[][] dp = new int[n+1][m+1];
        for(int i = 1;i <= n;i++){
            for(int j = 1;j <= m;j++){
                if(str1.charAt(i-1) == str2.charAt(j-1)){
                    dp[i][j] = dp[i-1][j-1] + 1;
                    if(dp[i][j] > maxLength){
                        maxLength = dp[i][j];
                        maxLastIndex = i-1;
                    }
                }else{
                    dp[i][j] = 0;
                }
            }
        }

        return str1.substring(maxLastIndex-maxLength+1,maxLastIndex+1);
    }
}
